高密度聚乙烯环境应力开裂机理的研究

An Investigation of Environmental Stress Cracking Mechanism in High Density Polyethylene

应用ＦＴＩＲ，ＤＳＣ，ＤＭＡ技术，从高聚物具有结构多重性和形变不均一性出发，定性地探讨了ＨＤＰＥ的ＥＳＣ开裂机理。在应力作用下ＨＤＰＥ的形变不均一性所形成的微裂纹，就成为具有各自不同利害程度的自然内存缺陷，从而活性介质获得了渗透到ＨＤＰＥ内部的机会，使ＨＤＰＥ表面能下降，导致应力集中链的滑脱和解缠，当滑脱和解缠的分子链积累到某临界值时，便呈现了宏观脆性开裂。并根据ＨＤＰＥ的ＥＳＣ开裂机理，提出了改善ＨＤＰＥ的ＥＳＣＲ性能的途径。ＨＤＰＥ的ＥＳＣＲ性能的提高取决于对其影响因素的最佳利用。

The environmental stress cracking (ESC) behaviors of high density polyethylene (HDPE) was qualitatively investigated by the measurements of FTIR, DSC and DMA,then the mechanism of ESC was also discussed. The inherent defects with different domage extent as microcracks in HDPE arc resulted from the structural multiplity and the non-uniformity of deformation under the action of stress. Thus the active reagents have a more chance to permeate into the interior of defcts than the bulk of HDPE, so it makes the surface energy of HDPE to decrease and the entangled molecular chains in the stress concentrated area to slip and pull-out. When the number of slipped out pulledout chains reaches a critical value, the HDPE sample shows macro fracture. Based on the above mechanism some method for improvement of ESC behoviors were proposed.lt is evidenf that the degree of improvement in ESC behaviors mainlg determined by the ultimating the best conditions of these influential factors.